The present invention is directed at an organic material having improved oxidation stability and/or improved anti-wear properties. More specifically, the present invention is directed at an improved lube oil comprising a basestock, and salts of copper and molybdenum.
Organic compounds, particularly those comprising relatively long hydrocarbon segments, are subject to autoxidation when they are contacted with oxygen. This, in turn, results in the deterioration of the base material, often leading to increases in the total acidity and sludge formation.
Several methods previously have been proposed to prevent or minimize autoxidation. In one method, certain reducing agents are used which are selectively oxidized by oxygen present, thereby preventing the formation of undesired oxygenated compounds, such as hydroperoxides.
In another process, peroxide removers or decomposers are utilized which complex with or decompose the peroxide immediately after formation to a product which will not produce additional free radicals.
In another process, materials generally classified as peroxide removers or decomposers are utilized.
U.S. Pat. No. 4,122,033 discloses an oxidation inhibitor and a method for using the oxidation inhibitor for hydrocarbon materials, particularly lube oils. This patent discloses that one or more transition metal containing compounds can be utilized in combustion with one or more other peroxide decomposer compounds as oxidation inhibitors in organic compositions subject to autoxidation. Among the transition metal compounds useful according to the patent are the salts of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, zirconium, niobium, molybdenum, tellurium, ruthenium, rhodium, palladium, and silver, to mention a few. This patent further states, at column 8, that when a combination of metals is used a synergistic effect will be noted if the sum of electromotive force voltages favors the presence of the stronger inhibitor and/or the weaker catalyst and is, generally, positive. Additionally the combination will be effective as a corrosion inhibitor at concentrations of about 100 ppm by weight, or less, when the amount of peroxide decomposer complexing agents or the like approaches 20,000 ppm by weight. In effect the effectiveness of the transition metal compounds is dependent upon relatively high concentrations of the peroxide decomposer compounds. For this and other reasons there remains a need for an additive for a lube oil having improved oxidation performance.
It also would be desirable to provide an additive for a lube oil which would permit the level of phosphorus in the lube oil to be lowered without adversely affecting the oxidative stability of the lube oil.
It also would be advantageous to provide a lube oil having improved anti-wear properties as compared to currently available products.